1. Field of the Invention
This invention relates to an upper thread holding device of a sewing machine having a thread cutting device.
2. Discussion of the Prior Art
An end of a thread sometimes becomes tangled, which constitutes a so-called nest on the back of a work piece such a cloth to be sewn when a sewing machine begins to sew the object. In order to avoid entanglement, a sewing machine including an upper thread holding device has been developed. In operation of this sewing machine, the upper thread holding device holds an upper thread which is cut in the last sewing operation, and the upper thread holding device releases or detaches therefrom the upper thread at the start of the next sewing operation. But the thread is cut only once at the end of the last sewing operation so that the length of the upper thread which extends from a hole of a needle is not even. Moreover, in case that the length of the upper thread which projects out from the workpiece is long, the tangled thread occurs at the back of the object and the finish is not good.
In order to shorten the length of the upper thread which is extended from the object, another sewing machine has been proposed in which the cutting of the upper thread is established at the start of the sewing operation as well as that at the end of the previous sewing operation. For instance, such a machine is disclosed in Japanese Utility Model Publication No. 2-14771 published in 1990 after examination. Referring to FIG. 8 showing the above mentioned machine, a needle-through groove 71 is formed at the center of a pressure foot 70 and a guide groove 72 is formed at the terminal end of the needle-through groove 71. A stationary blade 73 is fixed on the back of the pressure foot 70 and an edge 73a of the stationary blade 73 is disposed so as to traverse the guide groove 72. A thread holding member 74 catching an upper thread T is set above the pressure foot 70 so as to be able to be moved toward and from the upper thread T.
In operation of this machine, the thread holding member 74 advances and holds the upper thread T when a needle A is at its upper dead point. After catching the thread T the thread holding member 74 retracts. Sewing operation starts according to the above mentioned situation while another thread C between an object 75 to be sewn and the thread holding member 74 is being guided into the guide groove 71 of the pressure foot 70 as the object 75 is fed. At least the thread C is cut by the stationary blade 73 fixed to the pressure foot 70.
In the above mentioned construction, however, the distal end of the thread T is always cut while the thread T projects from upper surface of the object 75. It is not good for the quality of the sewed object that the distal end of the thread T projects therefrom.